Environmental disturbances are measured with a sensor positioned near the instrument to be protected and are cancelled by a real-time reverse field generated with a feedback controller and cable loops (or room coils) positioned around. The cancellation is continuous and can adapt to fluctuating disturbances.

This method is an effective and cost-efficient alternative to expensive magnetic field shielding, for example with mu-metal.

How do magnetic fields arise?

Besides natural magnetic fields that exist everywhere in the universe, the majority of problems encountered when operating sensitive devices arise from low-frequency magnetic fields that are caused by human activities, such as those emanating from electrical power cables, railways vehicles, elevators, etc. These fields occur as soon as electricity flows through a conductor.
Without suitable shielding, they expand outwards in a circular form and are quite capable of passing through most materials unhindered.

Active magnetic field cancellation: cost-efficient and effective

Magnetic field compensation has established itself as the most cost-effective solution. With this method the magnetic field is continuously measured and a compensation device, which includes the necessary control electronics and power amplifier for the direct connection of compensation coils, generates an opposing field. The compensation coils can be made of coiled cables that are laid at the edges of the laboratory, or as a complete solution integrated in a self-supporting aluminium frame.